The rather eye-catching title of this article posed a simple question – is there an association between complete intraoperative handover of anaesthesia care and adverse postoperative outcomes?

The exposure of interest was the complete intraoperative handover of anaesthesia care from the primary anaesthetist to the replacement anaesthetist. This did not include when breaks were being given. The transfer of care was symbolised by the billing code E005C.

Data collection

Data was gathered from all hospitals in Ontario, Canada between 2009 and 2015 from all adults over the age of 18 undergoing major surgeries with an estimated duration of at least 2 hours and requiring at least 1 night postoperative hospital admission. All surgery types were included. Patients having multiple surgeries within the accrual period were only included for their first eligible surgery, and patients who had surgery within the same surgical sub-group within the previous year were excluded to reduce the probability of complicated surgeries requiring revision or reoperation soon after initial operations.

Primary outcome

The primary outcome was a composite of all-cause death, hospital readmission, or major postoperative complications, all within 30 postoperative days. Secondary outcomes were the individual components of the primary outcome.

Results

313066 patients were found eligible for inclusion. 307125 were in the no handover group, with 5941 in the handover group. To account for the unequal groups, inverse probability of exposure weighting based on the propensity score was used to estimate adjusted exposure effects.

In the raw data, the primary outcome occurred in 44% in handover group vs 29% in no handover (risk difference [RD], 14.1% [95% CI, 12.8% to 15.3%]). Having a complete handover was associated with worse outcomes for each component of the primary outcome.

When adjusted, complete handover remained statistically significantly associated with an increased incidence of the primary outcome (adjusted [aRD], 6.8% [95% CI, 4.5% to 9.1%]). There was also an increase in all-cause death and major complications within 30 days but not with hospital readmissions.

Appraisal of the trial

Pros:

Large sample size, multi-centre study

All surgery types were included

Many outcome events occurred, increasing the statistical power

Comprehensive follow up of patients

Only physicians used – removes confounder cf nurse anaesthetists

Statistical models involved multiple variables, thus making them more accurate

Cons:

Large difference in unadjusted groups (252098 vs 4326)

Complex stats used to create comparable groups

‘Shotgun approach’ to statistical analysis

Several important confounders not included in model, e.g.

case start time

case complexity

experience of surgeon

experience of replacement anaesthetist

time of handover

Patients more likely to experience an adverse outcome also more likely to have a handover

Discussion

Despite the large sample size, there was a large discrepancy between the two groups in terms of numbers. The authors used very complicated statistics to create two groups of equal size. The headline findings here are based on these complicated statistics, which themselves come with their own limitations. The authors also left out several important confounders in their statistical model, potentially meaning unadjusted confounding may still exist if the unmeasured factors influenced treatment selection. The implications of this study are potentially quite far reaching, and can have a potential medicolegal impact on patient care if proven to be true. Conversely however, there are a plethora of studies that show that handover of patients improves patient outcomes. The fact that the vast majority of surgeries involved a complete handover probably shows that anaesthetists feel safer handing over patients than not, and this unlikely to stop any time soon.